Telephone system



1,632,051 W. WHITNEY TELEPHONE sys'rsu v Filed July 2a, 1926 2Sheets-Sheet 1 June 14, 1927.

Jl me 14. 1921. 1,632,051

. w. WHITNEY TELEPHONE SYSTEM Filed July 28, 1926 a Sheets-Stieet 2Patented June 14, 1927.

UNITED STATES PATE T OFFICE; Y

WILEY I EY, 0F nnsr ORANGE, NEW J RS Y, ASSIGNOR T0 BELL TELEPHONELABORATORIES, INCORPORATED, OF NEW Yomg'N, Y., A OORPoRATIjoN OF NEWYORK.

TELEPHONE SYSTEM.

Application filed July 28,

This invention relatesto telephone systems, and more particularly toimprovements in the establishment and supervision of connections overstraightfoiwvard trunks;

Heretofore in trunking systems of this type it has been customary toprovide, at the incoming ends of the straightforward trunks, means forassociating therewith a circuit, containing a dialing equipment anda Boperatorstelephone set, which is common to a plurality of such trunks. Asequence circuit is often interposed between the trunks and the commonequipment for the connection of said equipment with the straightforwardtrunks in the order in which such trunks are taken for use. Trunks ofthis type may terminate in plugs at the incoming end andbe equipped forextension to various kinds of wanted subscribers lines. Con: nection maybe extended either directly to a subscribers line, or throughintermediate interofiice trunks leading to operators positions at adistant exchange or to automatic equipment of a distant exchange. Fromtheseoperators positions a wanted subscriber may be reached through amanually completed connection, or through automatic switches that may beoperated by the actuation of the B opera-tors common dialing equipmentto associate a straightforward trunk with the wanted subscribersline.

According to the present invention there is provided an arrangementwhereby the common equipment,including a dial and a B operatorstelephone, is automatically associated with and preparedfor use with astraightforward trunk when said trunk is seized at. the originating endand whereby a signal consisting of a plurality of distinctive toneimpulses is automatically produced and transmitted to the operator atthe call originating end and to the B operator when the connectionbetween the common equipment and the seized trunk is completed.

According to another aspect of the invention the usual ringing relay isemployed for 1926. Serial No. 125,367. X

7 involving said trunk.

Moreoverjthere is provided means whereby the usual guard and disconnectlamp as-' sociated with a straightforward trunk is not locked inactuated condition when a trunk is seized but is free to release if theoperator at the originating end abandons the call before the commonequipment is connected totthe trunk. v

The invention has been illustrated in the accompanying drawings, inwhich 1 shows the incoming end of a straightforward trunlz arranged inaccordance with this invention. A port on of sequence circuit is alsoshown in this figure whereby the common equipment may be'connected insuccession to seize trunks, while Fig. 2 shows this common equipmentwhich includes, besides the operators telephone setand dial, anarrangement for producing a plurality of tone impulses.

Referring now in general to the circuit arrangements shown, astraightforward trunk l incoming from a distant exchange terminates in aplug 2 whereby connections may be extended to various types of lines,for example, to jack 4 of a tandem trunk that may terminate at a distantexchange at an incoming operators position or automatic equipment, orthrough a jack 3 directly to a wanted subscriber. This trunk; 1 isprovided with a guard and disconnect lamp 5 for the supervision of acall over this trunk and a sequence circuit through which the Boperators telephone set 6 and a dial 7 may be associated with the trunk.Of this circuit only a relay arrangement 8 individual to trunk 1 hasbeenshown together with a relay arrangement 9 which is common to a pluralityof trunks, it being understood that each trunk such as 1 ofthe samegroup is equipped withan individual relay arrangement such as8. Thislast mentioned common equipment 9 includes'a pilot lamp 10. The commonequipment shown in Fig. 2 includes besides the B operators set 6 anddial 7 a tone source 12 and a relay arrangement 13, whereby two impulsesof tone may be produced for transmission to the call originatingoperator and to the telephone set 6, and also a relay arrangement .14:whereby the common equipment may be manually disconnected from thetrunk 1. A relay arrangement for flashing the guard and disconnect lamp5 shown in Fig. 2 will be hereinafter described.

To clearly bring forth the various features of this invention adescription will now be made of a connection extending over trunk 1 to amanual subscriber and to an automatic subscriber and a description ofthe functions taking place when the operator at the originating exchangeabandons a call over trunk 1. Assuming then that the operator at theoriginating exchange has seized trunk 1, in a manner well known intheart by establishing a battery connection for the conductors of trunk 1,relay will operate over a circuit from the conductors, retardation coil21, left winding of relay 20 to ground and middle winding of relay 20,armature and back contact of relay 23 to ground. The operation of relay20 closes an obvious circuit for relay 2 which in operating closescircuit for the operation of relay 25 as follows: Battery, winding ofrelay 25, lower outer armature and back contact of relay 26, armatureand front contact of relay 2%- to ground. Relay 25 in operating opensthe tip conductor of trunk 1 at its upper outer armature and backContact and provides a circuit for the operation of relay 26 as follows:Battery, winding of relay 26 upper inner armature and back contact ofrelay 26, upper armature and back contact of relay 2?, upper innerarmature and front contact of relay 25 to ground. Relay 26 in operatingcloses a looking circuit for itself through its upper makebefore-breakcontacts to'ground at the armature and front contact of relay 24, andcloses a circuit for the lighting of guard lamp 5 as follows: Batte y,lower outer armature and back contact of relay 28, resistance 29, lowerinner arn'iature and front Contact of relay 26. lower outer arn'iatureand back contact of relay 2?, lamp 5 to'ground. lhe lighting of lamp 5indicates to the B oporator that trunk 1 has been seized.

If the common equipment shown in Fig. 2 has not been seized by any othertrunk at this time, battery will be supplied for the operation of relay30 over the following circuit: Battery, winding of relay 30, enter lowerarmature and front contact of relay 2, armature and front contact ofrelay 21 to ground. The operation of relay 30 closes a circuit for theoperation of relay 31 as follows: Battery, winding of relay 31,

lower armature and front contact of relay 30 through lowermake-before-break cont-acts of relays corresponding to relay 30individual to other trunks through the winding of relay 32, armature andback contact ofrelay 33 to ground. This circuit also causes theoperation of relay 32, hichin operating closes an obvious circuit forrelay 33 that removes the ground from the previously traced circuit andis locked with the relays 32 and 31 through the front contacts of relay32 to ground. Relays 32 and 33 are provided to insure that the lowestnumbered of the waiting trunks will be next connected to the commonequipment when released from the last trunk in the group in a mannerwhich will be set forth hereinafter. The operation of relay 31associates the common tip and ring conductors from the operatorstelephone set 6 with the tip and ring conductors of trunk l at its outerupper and lower armatures and front contacts.

Itshould be understood that the operators telephone set 6 is connectedthrough the plugs and jacks shown connected to the common talkingcircuit through the repeating coil 3 1 when. the B operator is inattendance at this position. Relay is, therefore, at such times operatedby a circuit from battery, winding of relay through the transmitter, theprimary of the repeating coil 34: to ground. Relay 35 in operatingcauses the operation through obvious circuits of relays 36 and 37, sothat a talking circuit from the operators telephone set ('3 is normallyextended to the upper and outer lower armatures of relays, such as 31,except that this circuit is broken at the contacts of relay at"? untilrequired as will be hereinafter described. The operation of relay 31closes a circuit for relay 38 as follows: Britt-my, resistance 29, innerlower armature and front contact of relay 26, enter lower armature andback contact of relay 2?, middle upper armature and front contact ofrelay 31, makebefore-break contacts of relay 39, winding of relay 38 toground. The operation of relay 3S closes an obvious circuit for theoperation of relay 39, which in operating closes an obvious circuit forthe lighting of pilot lamp 10 to indicate that a trunk is beingconnected to the. common equipment. This relay in operating alsotransfers the control over the operation of relay 38 from the battery atrelay 28 to battery through the winding of relay 25 through the innerupper armatures and front contacts of relays 31 and 30 and the outerupper armature and front contact of relay 39.

Another circuit closed by the operation of relay 39 is that for theoperation of relay 40 which may be traced as follows: Battery, lowerouter armature and back contact of relay28, resistance 29, lower innerarmature and front contact of relay 26, lower outer armature and backcontact of relay 27, upper middle armature and front contact of relay31, upper inner armature and front contact of'relay 39', right handarmature and front contact of relay 36, winding of relay 40 to ground.It should be noted'that this "relay 40 is in a connection to groundparallel to the connection toground of lamp 5. hen relay 40 attracts itsarmature an obvious circuit will be closed for'the slow to operate relay42, which in attractingits armature closes an obvious circuit for theoperation of slow to operate relay 43 on the operation of this lastmentioned relay a connection is closed to ground at its armature andfront contact for'theshunting of relay 40 and lamp 5. Relay 40 isreleased and lamp 5 is'extinguished. On therelease of relay 40 relays 42and 43 are released in succession and on the release of relay 43 theshort-circuit for relay 40 and lamp 5 is re moved so relay 40 isreoperated and lamp 5 is again lighted. This cycle of operations ofrelays 40, 42 and 43 is continuous, so that lamp 5' alternately becomeslighted and extinguished to indicate to the B operator that the commonequipment has been ciated with the trunk 1.

It will be noted that on the operation of relay 31 a circuit is closedfor the operation of relay 45 as follows: Battery, winding of relay 25,upper inner armatures and front contacts of relays 30 and 31, left handarmatureand front contact of relay 36, outer right hand armature andback contact of relay 72, winding of relay 45, normal makebefore-breakcontacts of this relay through the lower inner armature and back contactof relay 47 to ground. Relay 45 in operating provides a locking circuitfor itself independent of the ground at the relay 47, through itsarmature and front contact to ground. This relay 45 in operating alsocloses an obvious circuit for the operation of relay 48; Relay 48 inoperating provides a circuit from the tone device 12 to the tip and ringconductors of trunk 1, the primary of tone coil 49 of tone device 12being connected to ground through the inner right hand armature andfront contact of relay 48 and ri ht hand armature and back contact ofrelay 50, while the secondary of the tone coil 49 is connected to thetwo outer right hand armatures and front contacts of relay 48, the upperand lower outer armatures and back contacts of relay 47, upper outer andlower armatures and frontv contacts of relay 37, upper outer and lowerarmatures and back contacts of relay 51, upper andlower outerarmaturesandfront contacts of relay 31 through the upper "and lowerarmatures and back contacts of rela 53 winding of relay'7 5 onthe ringthrough the right hand windings of the repeating coil 54 to battery andground. Relay does not operate in this circuit due to the inclusion of acondenser-at the back coir tact of theupper armature of; relay 51. Aconnection i s-also established from the secondary of the coil 49 of thetone device to the upper armatures and back contacts of relay 47to theprimary winding of the repeating coil 56' associated with the receiverof the operators telephone set 6, so that a tone will now be transmittedthrough the 'repeating'coil 56 t0 the operators telephone frontcontacttoground for the primary of the repeating coil 79 so'that a tone is -againtransmitted to the operator at the distant end of trunk 1 and to the Boperators telephone set 6; The operation of relay 58 closes an obviouscircuit for the slow to operate relay '59,'which in operating closesan-obvious circuit for the operation of relay 47. The operation ofthisrela'y opens the original energizing circuit for relay 45 at itsinner lower armature and back contact and also opens the circuit fromthe secondary of the tone coil 49 to the tip and ring conductors leadingtothe trunk 1 and disconnects the repeating coil 56 so that the tonefrom the device 12 will cease to be transmitted to the two operators.These two impulses of tone indicate to'the B operator and to theoperator at the distant end of the trunk 1 that the B operatorstelephone set 6 has been connected to the trunk 1. This takes place onthe operation of relay 47 when the secondary of the transformer 34 isconnected through the upper outer and the lower outer armatures. andfront .contaots, through two of the contacts of relays 37, 51, 31 and 53to. trunk 1.

Conversationbetween the operator at the distant end and the B operatormay now take place and when the B operator receives the number of thewanted subscribers line she may initiate the desired connection byinserting plug 2 into jack 3 if a local subscriber is wanted. In thiscase a circuit is established through the sleevesof plug 2 and jack 3for the operation of relay 62. The operation of relay 62 completes thetip conductor fortrunk 1 to the terminals of plug 2 and jack 3 andcloses the circuit for the operation of relay 27 as follows: Battery,lower armature and front co'ntact'of relay 62, windingfof relay 27 toground. The

operation of relay 27 opens the original en- 7 "ergizing circuit forrelay 26 at its upperar- 'mature and back contact and at-i'ts-lower "oue aware and 1.3840 contact op ns the circuit for lamp '5, which is nowextinguished. This relay also closes a circuit for. ringing relay asfollows: Battery, winding of relay 65,- lower inner armature and backcontact of relay 28, lower innerarmature and front contact of relay 27armature and front contact of relay 2a to ground.

The operation of relay 65 connects ringing current from source 66through the ringing trip relay 67, upper middle armature and backcontact of relay 28 through the lower armature and front contact ofrelay 65 to the ring conductor of trunk 1 and a ground through the upperarmature and front contact of relay 65 to the tip conductor of trunk 1.This ringing current is transmitted to the subscriber connected to jack3. It should be noted that ringing is also inductively transmittedthrough condenser 68 and repeating coil 54 to the outgoing end of trunk1, so that the operator at this end will hear the ringing of the wantedsubscriber.

lVhen the wanted subscriber answers ringing trip relay 67 operates as iswell known in the art and by removing the ground from the outer contactof its armature causes re lay 28 to operate from the battery at thelower armature and front contact of relay 62. The operation of relay 28causes the release of ringing relay 65 and also ringing trip relay 67and ringing current is thereby removed from the trunk 1. The release ofrelay 65 establishes a connection for the tip and ring leads between therepeating coil 51- and the plug 2, so that relay will now becomeoperated through the subscribers loop. This relay in operating closes anobvious circuit for the operation of relay 23 and this relay which byattracting its armature applies battery to the tip conductor of trunk 1to cause a signal indication, as is well known in the art, to be made atthe distant operators position, indicating that the called subscriberhas answered.

It should be noted, however, that before conversation between thesubscriber at the distant end of trunk 1 and the wanted subscriber cantake place the B operators telephone set must be disconnected from thetrunk. This is done by having the B op erator actuate release key 70.-The operation of key 70 closes a circuit for relay 7-1 as follows:Battery, right hand winding of relay 71, right hand armature and backcontact of relay 72, upper inner armature and front contact of relay 37,outer left armature and back contact of relay 73 and key 70 to ground.-The operation of relay 71 closes a circuit for the operation of relay46 as follows: Battery, armature and front contact and left hand windingof relay 71, makebeforebreak contact of relay 72, right hand winding ofrelay 46 to ground. The operation ofrelay 4:6 closes a circuit frombattery at the ari'nature and front contact of relay 71 to the left handarmature and front contact of relay 46 through theleft hand winding ofthis relay to ground, and also through the left hand Winding of relay 72to ground. Relay 72 operates and breaks the original energizing circuitfor relay 46 which, however, is now held up from the battery on thearmature and front contact of relay 71 through its own left handarmature and front contact. Relay 72 in operating however opens theenergizing circuit for relay 71, but before this relay releases aconnection from battery at the armature. and front contact of this relayis connected through the left hand armature and front contact of relay72 to the left hand armature of relay 36, the purpose of which will beexplained later. Relay 72 in energizing closes locking'circuit foritself to battery through its right hand winding, inner right handarmature and front contact to the ground at key 70 and the release ofrelay 71 causes the release of relay 46. The operation of relay 72 alsoopens the circuit for relay 45, which in releasing causes the release ofrelay 18 and the release in succession of relays 50, 58, 59 and 47. Therelease of relay 47 opens the circuit from the operators telephone set 6to the tip and ring leads of trunk 1 and the temporary battery from thearmature and front contact of relay 71 mentioned above causes therelease of relays 25', 38 and 39 and extinguishes pilotv lamp 10. Relay25 now becomes locked in non-operated position due to the batteryconnected through its make-before-break contacts and upper outerarmature and front contact ofrelay 26. The release of relay 25 causesthe release of re lay 30 in the sequence circuit and the release of thisrelay causes the releaseof relays 31, and 33. Upon the release of relay32 the ground connection provided by relays 32 and 33 is opened for aninterval timed by the slow release of relay 33 so that if another relaysuch as 31 is in a condition to be energizedits circuit will not becompleted through the chain contacts of relays such as 30 until thedisconnection of the operators set 6 from the present trunk iscompleted. Upon the reapplication of this ground connection by therelease of relay 33 the lowest numbered of the waiting trunks will benext connected to the counting equipment because the circuit of therelay 31 of the lowest numbered trunk will be completed and the circuitof other relays such as 31 will be opened by the energization of therelay corresponding to relay 30 of such lowest numbered waiting trunk.The release of relay 25 also causes the release of relay 53 if the plug2 has been inserted in jack 3 before the operation of key 70 in whichcase this relay became operated on the operation of relay 28. Theoperation of relay 53 in this type of connection is believed of noimportance. The con nection from the operator at the distant end oftrunk 1 to the wanted subscribers line is now completed through contactsof the re-- lays 53, 25, and 62 so that conversation may now take placebetween these subscribers. V 1

hen conversation ceases and the wanted subscriber. hangs up hisreceiver, relay 75 releases, causing the release of relay 23, whichremoves the battery from the tip eon ductor of trunk 1, causing a.disconnect signal to be received at the distant operators position.This operator thereupon removes the plug from the jack associated withthe opposite end of trunk and thus causes the release of relays 20 and24. The release of relay 24 causes the release of relay 26. This closesa circuit for. thelighting of lam 5 and operation of relay 65 as follows:i attery, winding of ringing relay 65, inner lower armature. and frontcontact of relay 28, inner lower armature and back contact of relay 26,outerlower armature and front contact of relay 27, lamp 5 to ground.Then the B operator finds lamp 5 lighted, she will remove the plug2'from jack 3, causing the release of relays 62, 27, 28 and 65 and thecircuits are'now in normal con-. dition. In this type of connection theoperation of the ringing relay 65 atthistime is of no importance.

If the operator at the distant end of trunk 1 should abandon the call byremoving the plug of her cord from the'jack of trunk 1 before the Boperator had time to operate her release key 70, the B operatorstelephone set 6 and dial 7 would be automatically disconnected from thetrunk 1,tha,t is, relays 20 and 24 will release and the release of relay24 will cause the release of relay- 26 and relays 30 and 31. The releaseof relay 26 causes the release of relay 25. If plug 2 is inserted injack3, relay 53 will also be released at this time and in that case the lamp5 will light on the release of relay 26 so that the B operator will nowremove plug 2 from jack 3. The release of relays 30 and 31 willnaturally cause the release of relays 38and 39, 32.and 33, and relays45. 48, 50, 58, 59 and 47 so that the common equipment will be restoredto normal condition and is now therefore available for use with othertrunks.

If the wanted subscriber is one that can be reached only through anintermediate trunk such a trunk terminating, for example, in jack 4,such trunk may be selected by the usual call wire method and theconnection established at the distant exchange through the usual manualcord circuit. If an automatic subscriber is desired, the connectionswill be established at the distant exchange to automatic switches sothat the B operator may dial the desired subscribers number. As themeans of extending the connection to an automatic exchange subscriberforms nopart of this invention, no showing has been made thereof,norwill any further descriptions be made in this respect, except to showhow the B operator may dial such a subscriber. Under thesecircumstances, on insertion of plug 2 into jack 4, the operations willbeidentical to the operations described for the connection through jack 3,except that the ringing will be tripped immediately to cause theoperation 1 of relay 28. It will be noted that on the operation of relay28 relay 53 operates from ground-at the upper inner armature and frontcontact of relay 25 to the battery ap plied at the upper inner armatureand front contact of relay 26. The operation of relay 53 connects thetip of plug 2 to the tip conductor of the common equipment through theupper outer armature of relay 31 independent of relay 25, so that thecommon equipment is now connected to plug 2. The B operator may nowactuate her dial 7 and on the operation of the dial-from normal a groundconnection is made to the off-normal contacts of the dial for theoperation of relay 73 over an obvious circuit and on the operation ofrelay 73 a circuit is closed for the operation of relay 51 as follows:Battery, upper outer armature and front contact of relay 26, upper outerarmature and front contact of relay 28, upper outer armature and frontcontact of relay 30, winding of relay 51, right hand armature and frontcontact of relay 73 to ground. On the operation of relay 51 ground fromthe middle left hand armature and front contact of relay 73 is connectedthrough the lower armature and front contact of relay 51 to the ringconductor of plug 2 through the trunk connected to jack 4, and a groundis also connected through the pulsing contacts of dial 7and upper innerarmature and front contact of relay 51 to the tip conductor of plug 2and'rthe tip conductor of the trunk connected to 3 jack 4. This second"mentioned connection to ground will be interrupted on the return of thedial to normal in accordance with the digit dialed, to cause theoperation of the usual pulsing relays in the automatic switches at thedistant end thereby manipulating the switches to select the wantedsubscribers number as is well known inthe art. Relays 73 and 51 arereleased between the digits so that the B operators telephone set 6 willbe connected through the induction coil 34 and the talk ing conductorsof the plug 2 to the distant switches. This is to enable thetransmission of busy tone to the operators telephone set 6 in-case abusy condition is encountered. After dialing is completed, the Boperator releases her dial and telephone set by the operation of key 7 Oin the manner hereinbefore described and the Subscribers may beginconversation. After the subscribers have finished their conversation thedisconnection may take place in the same manner as when a manualsubscriber is connected to jack 3. v a

As mentioned in connection with the description of the release of thetrunk lwhen the operator at the distant end removes a plug from the jackor trunk 1, relay 65 operates at the same time as lamp 5 is lighted. Inthis case the splitting of the trunk at the armatures and back contactsof relay 65 may be utilized as a disconnect signal. Relay 65 maytherefore serve two purposes, namely, to apply ringing current and tosplit the conductors of trunk 1 to produce a signal at the distant endof a connector trunk.

lVhat is claimed is:

1. In a telephone system, a trunk, a signal associated with said trunk,an operators telephone set and an impulse sender, means responsive tothe seizure of sad trunk for actuating said signal and for automaticallyassociating said telephone set and sender with said trunk, and meansefiective incident to the association of said telephone set and senderwith said trunk for actuating said signal in a different manner and fortransmitting a signal con'iprising a plurality of impulses of tonecurrent to said trunk and t said telephone set.

2. In a telephone system, a trunk, 21 line, a signal associated withsaid trunk, means for actuating said signal responsive to the seizure ofsaid trunk at its outgoing end, means .for interconnecting said trunkand line, means including a relay responsive to the interconnection ofthe trunk and line for disabling the signal and another relay undercontrol of said first relay for opening the trunk conductors andapplying ringing current to said line, means including another relayresponsive to the tripping of the ringing for releasing said secondmentioned relay, and means responsive to the release of the outgoing endof the trunk for reactuating said signal and for reactuating said second mentioned relay to reopen the trunk conductors.

3. In a telephone system, a trunk, a line, means for seizing said trunk,means for interconnecting said trunk and line, means including a relayoperating in response to the interconnection of said trunk and line foropening the trunk conductors and applying ringing current to said line,means responsive to the seizing of said line for releasing said relay todiscontinue the ringing and close the trunk conductors, and meansresponsive to the release of said trunk for reopcrating said relay toopen the trunk conductors without applying ringing current to the line.I

4. In a telephone system, a trunk, an operators telephone set and adial, a signal associated with said trunk, means responsive to theseizure of said trunk for actuating said signal and for automaticallyassociat ing said telephone set and dial with the trunk, meansefi'ertive incident to the automatic association of the telephone setand dial with the trunk for actuating said signal-in a different manner,and means for automatically releasing said telephone set and dial anddisabling the signal responsive to the release of said trunk.

5. In a telephone system, a trunk, a line, an operators telephone setand a dial, a signal, means responsive to the seizure-of the trunk foractuating said signal and automatieally associating the telephone setand dial with the trunk, means effective incident to the association ofthe telephone set and dial with the trunk for actuating said signal in adifferent manner and for applying a tone signal comprising a pluralityof tone current impulses to the trunk and to the operators telephoneset, means for associating the trunk with the line, a source of ring ingcurrent, means effective incident to the association of said trunk andline for disabling said signal before applying ringing current to theline and to the trunk and for WILEY WHITNEY.

